Theory of Systematic Absence of NaCl-Type (b-Sn–Type) High Pressure Phases in Covalent (Ionic) Semiconductors
نویسندگان
چکیده
Recent high pressure x-ray experiments show that, contrary to traditional expectations, the NaCl structure is not present in covalent semiconductors, and the diatomic b-Sn structure is absent in all compound semiconductors. We explain these systematic absences in terms of dynamical phonon instabilities of the NaCl and b-Sn crystal structures. Covalent materials in the NaCl structure become dynamically unstable with respect to the transverse acoustic TA[001] phonon, while ionic compounds in the b-Sn structure exhibit phonon instabilities in the longitudinal optical LOf00jg branch. The latter lead to predicted new high pressure phases of octet semiconductors. [S0031-9007(98)08188-5]
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